The propagation of ionization waves - influenced by irradiation of suitable wavelength
- Univ. of Greifswald (Germany)
The impact of external irradiation mainly at metastable transitions on the propagation of ionization waves in the positive column of a neon a low discharge is investigated. Effects of hysteresis, regions of existence of moving striations and the static current/voltage characteristic depending on the external circuit and on the axial location of the applied irradiation are observed experimentally. The many published experimental contributions show that the presence of striations - either standing or moving - is the normal situation in the diffusion range of pressure and that the homogeneous (i.e. striation free) positive column is the exception existing only for a limited range of currents and pressures. A slight change of one or the other of these parameters results in a transition from the homogeneous column to one containing moving striations or vice versa. Different types of moving striations are known (p-,r- and s- waves) which differ in the product of wavelength {lambda} and the electric field strength E (Novak-constant). It is assumed, that the metastable atoms are responsible for the appearance of p-waves and therefore the discharge was operated at a pressure of p{sub 0} = 1,7 Torr-cm and dc-discharge currents i{sub 0} = 1-20 mA. The length of the glass discharge tube was 1 = 500 mm with radius r{sub 0} = 1 cm. A hollow cathode and a plane electrode were used. The external resistance was varied between 20 kOhm and 1 MOhm additionally. The radiation of suitable wavelength was generated by a second discharge tube with emissive electrodes operated at a pressure of about 5 Torr-cm and discharge currents between 0,5A and 2A. Two hollow mirrors where the {open_quote}radiation-tube{close_quote} was centered between, guaranteed a constant light intensity around the investigated tube.
- OSTI ID:
- 232811
- Report Number(s):
- CONF-950749--
- Country of Publication:
- United States
- Language:
- English
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